Fix lint warnings and std lib deprecations

cmd/backup/config.go

@@ -7,7 +7,6 @@ import (
 	"crypto/x509"
 	"encoding/pem"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"regexp"
 	"strconv"
@@ -115,7 +114,7 @@ func (c *CertDecoder) Decode(v string) error {
 	if v == "" {
 		return nil
 	}
-	content, err := ioutil.ReadFile(v)
+	content, err := os.ReadFile(v)
 	if err != nil {
 		content = []byte(v)
 	}

cmd/backup/exec.go

@@ -10,7 +10,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"os"
 	"strings"
 
@@ -57,13 +57,14 @@ func (s *script) exec(containerRef string, command string, user string) ([]byte,
 			return nil, nil, fmt.Errorf("exec: error demultiplexing output: %w", err)
 		}
 		break
+	default:
 	}
 
-	stdout, err := ioutil.ReadAll(&outBuf)
+	stdout, err := io.ReadAll(&outBuf)
 	if err != nil {
 		return nil, nil, fmt.Errorf("exec: error reading stdout: %w", err)
 	}
-	stderr, err := ioutil.ReadAll(&errBuf)
+	stderr, err := io.ReadAll(&errBuf)
 	if err != nil {
 		return nil, nil, fmt.Errorf("exec: error reading stderr: %w", err)
 	}
@@ -152,9 +153,9 @@ func (s *script) runLabeledCommands(label string) error {
 		g.Go(func() error {
 			cmd, ok := c.Labels[label]
 			if !ok && label == "docker-volume-backup.archive-pre" {
-				cmd, _ = c.Labels["docker-volume-backup.exec-pre"]
+				cmd = c.Labels["docker-volume-backup.exec-pre"]
 			} else if !ok && label == "docker-volume-backup.archive-post" {
-				cmd, _ = c.Labels["docker-volume-backup.exec-post"]
+				cmd = c.Labels["docker-volume-backup.exec-post"]
 			}
 
 			userLabelName := fmt.Sprintf("%s.user", label)

cmd/backup/lock.go

@@ -15,10 +15,12 @@ import (
 // caller invokes the returned release func. In case the lock is currently blocked
 // by another execution, it will repeatedly retry until the lock is available
 // or the given timeout is exceeded.
+//
+//lint:ignore U1000 Keep unused function
 func (s *script) lock(lockfile string) (func() error, error) {
 	start := time.Now()
 	defer func() {
-		s.stats.LockedTime = time.Now().Sub(start)
+		s.stats.LockedTime = time.Since(start)
 	}()
 
 	retry := time.NewTicker(5 * time.Second)

cmd/backup/script.go

@@ -53,6 +53,7 @@ type script struct {
 	file  string
 	stats *Stats
 
+	//lint:ignore U1000 used in lock.go
 	encounteredLock bool
 
 	c *Config

internal/storage/ssh/ssh.go

@@ -7,7 +7,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"path"
 	"path/filepath"
@@ -46,7 +45,7 @@ func NewStorageBackend(opts Config, logFunc storage.Log) (storage.Backend, error
 	}
 
 	if _, err := os.Stat(opts.IdentityFile); err == nil {
-		key, err := ioutil.ReadFile(opts.IdentityFile)
+		key, err := os.ReadFile(opts.IdentityFile)
 		if err != nil {
 			return nil, errors.New("NewStorageBackend: error reading the private key")
 		}